Semiconductor substrate, and semiconductor device and method of manufacturing the semiconductor device

ABSTRACT

In a semiconductor substrate  1 , a plurality of semiconductor elements  2  having diaphragm structures are formed in the form of cells in the longitudinal direction and the lateral direction, and V-grooves  3  are formed by anisotropic etching continuously on only division lines  4  parallel formed in one direction, out of the division lines  4  which are orthogonal to each other and divide the respective semiconductor elements  2  individually.

FIELD OF THE INVENTION

The present invention relates to a semiconductor substrate having adiaphragm structure and a beam structure formed by thinning a part ofthe semiconductor substrate, which is typified by MEMS (Micro ElectroMechanical System), and a semiconductor device manufactured by dividingthe semiconductor substrate and a manufacturing method of thesemiconductor device.

BACKGROUND OF THE INVENTION

In the semiconductor devices which are manufactured by the abovedescribed MEMS and have diaphragm structures and beam structures thatare partially thinned, MEMS pressure sensors and MEMS accelerationsensors are included. Such sensors are generally manufactured bydividing a plurality of the above described diaphragm structures andbeam structures individually after the diaphragm structures and beamstructures are simultaneously formed in the semiconductor wafer process.For the division, the method for performing crushing by rotating aring-shaped dicing saw in which particles of diamond and CBN are held bya bond material at a high speed is most commonly used. Since themachining by the dicing saw is performed while cutting water is run forwashing out crushed chips and cooling down the frictional heat, and thediaphragm structures and the beam structures are brittle structures,there has been the problem that the diaphragm structures and the beamstructures are broken due to the pressure of the cutting water duringmachining by the dicing saw.

In recent years, as a method for solving such a problem, machining bylaser light has attracted attention, and an example of such machining isdisclosed in, for example, Japanese Patent No. 3408805.

In the manufacturing method by laser light disclosed in Japanese PatentNo. 3408805, a modified region by multiphoton absorption is formed in asemiconductor wafer, and the semiconductor wafer is divided by cleavagewith the modified region as the starting point. Multiphoton absorptionis the phenomenon in which even when energy of photon is smaller thanthe band gap of absorption of the material, namely, even when photon isoptically transmitted, by making the intensity of light very high,absorption occurs in the material. By aligning the focusing point oflaser light with the inside of the semiconductor wafer, the phenomenonof multiphoton absorption is caused, and the modified region is formedinside the semiconductor wafer. Then, by easily breaking the substratealong the dicing lane, with the modified region formed as the startingpoint, division without requiring cutting water is enabled.

The above described method for machining by laser light will bedescribed based on the drawings. FIG. 9 is a plane view showing thedivision lines and the periphery of the semiconductor substrate which isa lased machining workpiece, and FIG. 10 is a sectional view taken alongthe line C-C′ shown in FIG. 9 during laser processing. In FIGS. 9 and10, reference numeral 101 denotes a semiconductor substrate, referencenumeral 102 denotes a semiconductor element which constitutes thesemiconductor device formed in the semiconductor substrate 101,reference numeral 104 denotes the division line of the semiconductorelement 102, reference numeral 108 denotes laser light, referencenumeral 109 denotes a modified region, and reference numeral 110 denotesa cut portion (crack) occurring with the modified region 109 as thestarting point.

The process of the method of machining by laser light will be describedhereinafter.

First, the focusing point of the laser light 108 is aligned with theinside of the semiconductor substrate 101, and multiphoton absorption iscaused in a predetermined thickness direction.

Next, by scanning the laser light 108 along the center of the divisionline 104 while causing multiphoton absorption continuously orintermittently, the modified region 109 along the division line 104 isformed inside the semiconductor substrate 101, and the cut portion 110is formed.

Next, an external force is simultaneously applied to both ends of thesemiconductor substrate 101, the semiconductor substrate 101 is splitwith the modified region 109 as the starting point, and thesemiconductor device is formed. Since at this time, the cut portion 110is formed with the modified region 109 as the starting point, thesemiconductor substrate 101 can be easily broken with a relatively smallexternal force. Especially when the semiconductor substrate 101 is thin,the semiconductor substrate 101 splits naturally in the thicknessdirection even if the external force is not especially applied to thesemiconductor substrate 101.

Other than the above described method for machining by laser light, asthe method for solving the problem in which diaphragm structures andbeam structures are broken by the pressure of cutting water, reducingthe thickness of the machined portion by forming in advance a groove onthe division line by anisotropic etching or the like is performed. Thismethod is disclosed in, for example, Japanese Patent Laid-Open No.2001-127008.

In the manufacturing method disclosed in Japanese Patent Laid-Open No.2001-127008, an etching protection film is formed on the semiconductorsubstrate of an orientation plane (100) so as to open the division linein the longitudinal direction and the lateral direction first, andthereafter, anisotropic etching is performed. Herein, etching is stoppedon an orientation plane (111), and therefore, a V-groove with the angleof inclination of 54.7 degrees is formed. Next, an external force isapplied to the semiconductor substrate so that the V-groove is enlargedto divide the semiconductor substrate along the V-groove, and theindividual semiconductor devices are formed.

However, in the above-described known laser machining method disclosedin Patent Document 1, the following problem arises.

When the semiconductor substrate is thick, the semiconductor substratecannot be divided with the modified region by one scanning. Therefore, aplurality of modified regions are required to be formed parallel to thethickness direction by carrying out laser machining a plurality oftimes, and this leads to increase in tact required for machining.

In the above-described known method of manufacturing in which theV-groove is formed, disclosed in Patent Document 2, the followingproblem arises.

Since in the portion where the V-grooves intersect with each other inthe longitudinal direction and the lateral direction of the divisionlines, erosion of anisotropic etching differs from that in the otherportions, etching does not stop in the orientation plane (111) ifetching is performed excessively, and etching advances into anorientation plane (211), for example. In other words, when the V-grooveis to be formed simultaneously with the step of forming the diaphragmstructure requiring etching which is deeper than, for example, theV-groove, the intersection portions of the V-grooves are excessivelyetched, and the semiconductor substrate is penetrated. Therefore, thestrength of the semiconductor substrate is extremely reduced, and thesemiconductor substrate is broken at the time of handling thesemiconductor substrate.

DISCLOSURE OF THE INVENTION

The present invention has an object to solve these problems and providea semiconductor substrate capable of improving machining tact withoutdegrading quality of division when dividing the semiconductor substrateinto individual semiconductor devices, a semiconductor device and amethod of manufacturing the semiconductor device.

In order to attain this object, the semiconductor substrate of thepresent invention includes grooves continuously formed on only thedivision lines formed parallel in one direction, out of the divisionlines in the longitudinal direction and the lateral direction toindividually divide a plurality of semiconductor elements formed in ashape of cells in the longitudinal direction and the lateral direction.

With this configuration, the grooves are formed on only the divisionlines formed parallel in one direction, out of the division linesorthogonal to each other in the longitudinal direction and the lateraldirection, whereby, the thickness of the semiconductor substrate in thedivision line portions where the grooves are formed is thin and isnotched, and can have the structure in which stress easily concentrateswhen division by cleavage or the like is performed.

The method of manufacturing the semiconductor device of the presentinvention comprises a step of forming grooves by etching continuously ononly division lines formed parallel in one direction, out of thedivision lines in the longitudinal direction and the lateral directionin order to individually divide a plurality of semiconductor elementsformed in the form of cells in the longitudinal direction and thelateral direction in the semiconductor substrate, a step of formingmodified regions inside the semiconductor substrate by irradiating laserlight along the division lines in the aforesaid longitudinal directionand lateral direction respectively with the focal points aligned withthe inside of the aforesaid semiconductor substrate, and a step offorming individual semiconductor devices by dividing the semiconductorsubstrate along the division lines in the longitudinal direction andlateral direction by applying an external force to the aforesaidsemiconductor substrate.

By this manufacturing method, the grooves are formed by etching so as tobe in series on only the division lines formed parallel in onedirection, out of the division lines orthogonal to each other in thelongitudinal direction and the lateral direction, and thus, theintersection portions of the grooves for which control of etching isextremely difficult are not formed. Therefore, stable grooves can beformed extremely easily. The substrate is divided into the individualsemiconductor devices along the division lines where the continuousgrooves are formed, so that as compared with the case where the groovesare not formed, division with excellent straightness can be performedeasily.

The semiconductor device of the present invention is a semiconductordevice manufactured by the above described method, wherein chamfering isperformed for only two sides opposed to each other in a back surfaceside of each of the individual semiconductor devices.

With this configuration, chamfering is performed for the two sidesopposed to each other on the back surface side, and therefore, duringsubstrate mounting which is the post process thereof, the die bondmaterial used in bonding of the semiconductor device and the substratecan be restrained from creeping up to the side surface of thesemiconductor device. Since chamfering is not performed to the other twosides, the area of the back surface of the semiconductor device is notreduced, and bond area during tie bonding can be secured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plane view of a semiconductor substrate in one embodiment ofthe present invention;

FIG. 2 is a plane view showing a periphery of division lines of thesemiconductor substrate;

FIGS. 3A and 3B are a sectional view taken along the line A-A′ and asectional view taken along the line B-B′ in FIG. 2;

FIG. 4 is a flow chart of a method of manufacturing a semiconductordevice in one embodiment of the present invention;

FIGS. 5A to 5F are sectional views of the semiconductor substrateshowing the process steps of the method of manufacturing thesemiconductor device in sequence by using the sectional views takenalong the line B-B′ shown in FIG. 4;

FIGS. 6A and 6B are sectional views showing the method of manufacturingthe semiconductor device;

FIG. 7 shows a plane view, a cross-sectional view and a longitudinalsectional view of the semiconductor device after being divided from thesemiconductor substrate in one embodiment of the present invention;

FIG. 8 is a sectional view of a semiconductor substrate on which thesemiconductor device is mounted;

FIG. 9 is a plane view of a conventional semiconductor substrate; and

FIG. 10 is a sectional view showing a method of manufacturing aconventional semiconductor device.

DESCRIPTION OF THE EMBODIMENT(S)

An embodiment of the present invention will now be described withreference to the drawings.

With reference to FIGS. 1 to 3, a semiconductor substrate of the presentinvention will be described. In FIGS. 1 to 3, reference numeral 1denotes a semiconductor substrate made of Si single crystal, referencenumeral 2 denotes a semiconductor element constituting a semiconductordevice, reference numeral 3 denotes a V-groove (one example of agroove), reference numeral 4 denotes a division line and referencenumeral 5 denotes a diaphragm.

A plurality of semiconductor elements 2 are formed in the form of cellsin the longitudinal direction and the lateral direction in thesemiconductor substrate 1 as shown in FIGS. 1 and 2.

A plurality of semiconductor elements 2 are divided by the divisionlines 4 as shown in FIG. 2. In this case, the division lines 4 aredivision regions set when the semiconductor elements 2 are dividedindividually from the semiconductor substrate 1. The division lines 4are formed so as to be orthogonal (cross) in the longitudinal directionand the lateral direction, and as shown in FIGS. 1 to 3, out of thedivision lines orthogonal to each other, on only the division linesparallel with one of the longitudinal direction and the lateraldirection (in the drawing, on the division lines in the longitudinaldirection), the V-grooves 3 are formed. These V-grooves 3 are formed bythe orientation planes (111) with the inclination angle of 54.7 degrees,for example.

As shown in FIG. 3B, the diaphragm 5 is formed in each of thesemiconductor elements 2.

As described above, the V-grooves 3 are formed on only the divisionlines parallel in one direction, out of the division lines 4 orthogonalto each other in the longitudinal direction and the lateral direction,so that the semiconductor substrate 1 in the portions of the divisionlines 4 where the V-grooves 3 are formed is small in thickness, is in anotched shape, and can have the structure where stress easilyconcentrates when division by cleavage or the like is performed.Therefore, when the modified region to be the starting point fordividing the semiconductor substrate 1 into the individual semiconductorelements 2 is formed inside the semiconductor substrate 1, in the stepof dividing the semiconductor substrate 1 into the individualsemiconductor elements 2 which is a post process, the number of times oflaser light scanning can be made smaller as compared with that in thecase of the division line in which no groove is formed, as a result ofwhich, machining tact can be made short, and stable division withfavorable straightness is enabled.

Next, with reference to FIG. 4 and FIGS. 5A to 5F, a method ofmanufacturing the semiconductor device of the present invention will bedescribed. In FIGS. 5A to 5F, reference numeral 6 denotes an etchingmask, reference numeral 7 denotes an expanded tape, reference numeral 8denotes laser light, reference numeral 9 denotes a modified region,reference numeral 10 denotes a crack (cut portion) with the modifiedregion as a starting point, and reference numeral 11 denotes asemiconductor device after individual semiconductor elements 2 are cutout from the semiconductor substrate 1.

As shown in FIG. 4, the method of manufacturing the semiconductor deviceof the present invention comprises the following steps of: “formingV-grooves continuously on only division lines parallel in thelongitudinal direction by anisotropic etching” (forming grooves byetching); “forming modified regions inside the semiconductor substrateby irradiating laser light along the orthogonal division lines with thefocal points aligned with the inside of the semiconductor substrate”(forming the modified regions inside the semiconductor substrate); and“dividing the semiconductor substrate into individual semiconductordevices along the orthogonal division lines by applying an externalforce to the semiconductor substrate” (forming the individualsemiconductor devices) in this sequence.

First, “the step of forming the V-grooves continuously on only thedivision lines parallel in the longitudinal direction by anisotropicetching” will be described.

Namely, as shown in FIG. 5A, first, the etching mask 6 is formed on thesemiconductor substrate 1 on which a plurality of semiconductor elements2 are formed, and division lines (not shown) for dividing the individualsemiconductor elements 2 are set. The etching mask 6 is formed so thatthe regions where the diaphragms 5 and the V-grooves 3 are desired to beformed are opened. At this time, the openings of the etching mask 6 forforming the V-grooves 3 are formed on only the division lines 4 parallelin one direction.

In this case, for example, the etching mask 6 is formed by forming amaterial such as a silicon oxide film by using a CVD method, and then,patterning the material with a lithography technique. Though not shown,the etching mask is left on the entire surface where the semiconductorelements 2 are formed.

Next, as shown in FIG. 5B, the diaphragms 5 and the V-grooves 3 areformed by anisotropic etching. In this case, as an anisotropic etchingsolution, for example, a KOH solution, and a TMAH (tetramethylammoniumhydroxide) solution are used. At this time, the V-grooves 3 are formedon only the division lines 4 parallel in one direction, and thus, theV-grooves 3 do not have the intersecting patterns. Therefore, etching ofthe semiconductor substrate 1 comprised of the Si single crystalsubstrate does not cause abnormal erosion in the intersecting patterns,and reliably stops the process of etching on the orientation plane(111). Therefore, even when the diaphragms 5 and the V-grooves 3differing in etching depth are simultaneously formed, they can bestopped in the depth at an inclination angle of 54.7 degrees. In otherwords, the depth and width of the V-groove 3 can be determined by theopening width of the etching mask 6.

Next, as shown in FIG. 5C, the etching mask 6 is removed. For removingthe etching mask 6, for example, a BHF solution is used. Herein, theetching mask 6 is removed, but unless removal is especially necessary,the etching mask 6 may be left.

Subsequently, “the step of forming the modified region inside thesemiconductor substrate by irradiating laser light along the orthogonaldivision lines respectively with the focal points aligned with theinside of the semiconductor substrate” will be described.

That is, as shown in FIG. 5D, the semiconductor substrate 1 is mountedto the expanded tape 7 first.

Next, as shown in FIG. 5E, laser light 8 is irradiated along thedivision lines 4 orthogonal to each other respectively with the focalpoints aligned with the inside of the semiconductor substrate 1, and themodified regions 9 are formed inside the semiconductor substrate 1. Atthis time, scanning of the laser light 8 in the longitudinal directionis carried out along the lines of the V-grooves 3 and is carried out sothat micro-cracks occurring from the modified regions 9 develop into theV-grooves 3.

Subsequently, “the step of dividing the semiconductor substrate into theindividual semiconductor devices along the division lines orthogonal toeach other by applying an external force to the semiconductor substrate”which is carried out finally will be described.

Specifically, as shown in FIG. 5F, by applying the external force to theexpanded tape 7, the cracks 10 are developed from the modified regions 9formed respectively along the division lines 4 orthogonal to each otherto divide the semiconductor substrate 1, whereby the individualsemiconductor devices 11 are formed.

Here, when the semiconductor substrate 1 is thick, division can befacilitated by forming a plurality of modified regions 9 by carrying outscanning of the laser light 8 a plurality of times, but as shown inFIGS. 6A and 6B, division is possible if the number of times of scanningthe laser light 8 along the division lines 4 where the V-grooves 3 areformed is smaller than the number of times of scanning the laser light 8along the division lines 4 where the V-grooves 3 are not formed.

FIG. 6A is an enlarged sectional view taken along the B-B′ line of theabove described semiconductor substrate 1, and shows modified regions 9a and 9 b in the depth direction formed along the division line 4 wherethe V-groove 3 is formed when the number of times of scanning of thelaser light 8 is two. FIG. 6B is an enlarged sectional view taken alongthe line C-C′ of the semiconductor substrate 1 in the longitudinaldirection along the semiconductor element 2 with the diaphragm 5 formedtherein, and shows modified regions 9 a, 9 b and 9 c in the depthdirection formed along the division line 4 where the V-groove 3 is notformed when the number of times of scanning of the laser light 8 isthree.

As described above, with the configuration of the semiconductorsubstrate 1 and by the method of manufacturing the semiconductor device11, when forming the modified region 9 to be the starting point fordividing the semiconductor substrate 1 into the individual semiconductordevices 11, the number of times of scanning the laser light 8 along thedivision line 4 where the V-groove 3 is formed can be made smaller thanthe number of times of scanning the laser light 8 along the divisionline 4 without the V-groove 3, the machining tact can be shortened, andstable division with favorable straightness is enabled.

Since the V-grooves 3 are formed by etching so as to be in series ononly the division lines formed parallel in one direction, out of thedivision lines 4 orthogonal to each other, the intersection portions ofthe V-grooves 3 for which control of etching is extremely difficult arenot produced, and thereby, the stable V-grooves 3 can be formedextremely easily. Since the semiconductor substrates 1 is divided intothe individual semiconductor devices 11 along the division lines 4 wherethe continuous V-grooves 3 are formed, division with excellentstraightness can be made easily as compared with the case where theV-grooves 3 are not formed.

Formation of the V-grooves 3 is performed simultaneously with theanisotropic etching step of forming the diaphragm structure. Therefore,the step is not especially increased, and increases in cost and in leadtime can be avoided.

The semiconductor devices 11 individually divided from the semiconductorsubstrate 1 by the above described method of manufacturing thesemiconductor device 11 becomes the semiconductor devices each havingthe diaphragm structure as shown in FIG. 7. In FIG. 7, reference numeral11 denotes the semiconductor device after being individually divided,reference numeral 12 denotes a chamfer which is made when thesemiconductor device is divided with the vertex of the V-groove as thestarting point, and the chamfers 12 are formed at only two sides opposedto each other in the back surface side of the individual semiconductordevice 11.

As shown in FIG. 7, the portion of the chamfer 12 corresponding to theportion where the V-groove 3 is formed is disposed at the long side ofthe semiconductor device 11. That is, as the division line 4 where theV-groove 3 is formed, the division line along the long side of thesemiconductor device 11 is selected, and the V-groove 3 is formedthereon.

Semiconductor devices are generally broken easily when they are slim,and the starting point of breakage is a crack formed at the long side.Thus, by chamfering the long side, the crack to be the starting point iseliminated, and therefore, the transverse strength of the semiconductordevice is remarkably increased. In other words, chipping of the longside which leads to reduction in the transverse strength of thesemiconductor device 11 is suppressed, and the semiconductor device 11with excellent mechanical strength can be obtained. Since chamfering isnot performed for the short sides, the area of the back surface of thesemiconductor device 11 at the short side is not reduced, and the bondarea during die bonding can be secured.

FIG. 8 shows a sectional view of the state in which the semiconductordevice of the present invention is mounted on a substrate. In FIG. 8,reference numeral 13 denotes a mounting substrate, and reference numeral14 denotes a die bond material for bonding the mounting substrate 13 andthe semiconductor device 11.

Bonding of the semiconductor device 11 and the mounting substrate 13 isusually performed with the die bond material 14. When the bonding isperformed, the coating amount of the die bond material 14 needs to bestrictly controlled in order to control creeping-up to the side surfaceof the semiconductor device 11. As shown in FIG. 8, when the chamfer 12is applied to the semiconductor device 11, creeping-up of the die bondmaterial to the side surface of the semiconductor device 11 issuppressed by the surface tension of the chamfer 12, and therefore,control can be made extremely easy as compared with the conventionalunit. Since chamfering is not performed for the other two sides (theshort sides), the area of the back surface of the semiconductor device11 at the short side is not reduced, and the bond area during diebonding can be secured.

In this embodiment, the semiconductor substrate 1 and the semiconductordevice 11 include the diaphragm structures formed therein, but may notbe especially limited to the diaphragm structure.

In this embodiment, the grooves formed on only the division lines formedparallel in one of the longitudinal direction and the lateral direction,out of the division lines orthogonal to each other, are formed in theV-grooves, but the grooves are not limited to the V-grooves, and may beformed in the U-shaped grooves. The grooves are formed by anisotropicetching, but can be formed by dry etching.

The semiconductor substrate, and the semiconductor device and the methodof manufacturing the semiconductor device of the present invention aresuitable for manufacturing the semiconductor device without increasingthe machining cost and reducing the quality of machining in division ofthe silicon substrate and the compound semiconductor substrate, and areuseful for division especially when manufacturing an MEMS sensor and thelike having diaphragm structures.

1. A semiconductor substrate in which a plurality of semiconductorelements constituting semiconductor devices are formed in the form ofcells in the longitudinal direction and the lateral direction, anddivision lines are set in said longitudinal direction and lateraldirection to divide said plurality of semiconductor elementsindividually, wherein grooves are continuously formed on only thedivision lines formed parallel in one direction, out of the divisionlines in said longitudinal direction and lateral direction.
 2. Thesemiconductor substrate according to claim 1, wherein the semiconductordevices formed by being divided along said division lines aresemiconductor devices each having a diaphragm structure.
 3. Thesemiconductor substrate according to claim 1, wherein the grooves formedon said division lines are V-grooves.
 4. A method of manufacturing asemiconductor device for manufacturing semiconductor devices byindividually dividing a plurality of semiconductor elements constitutingthe semiconductor devices from a semiconductor substrate in which aplurality of semiconductor elements constituting the semiconductordevices are formed in the form of cells in the longitudinal directionand the lateral direction, and division lines are set in saidlongitudinal direction and lateral direction to divide said plurality ofsemiconductor elements individually, comprising the steps of: forminggrooves by etching continuously on only the division lines formedparallel in one direction, out of the division lines in saidlongitudinal direction and lateral direction; forming modified regionsinside the semiconductor substrate by irradiating laser light along thedivision lines in said longitudinal direction and lateral directionrespectively with focal points aligned with an inside of saidsemiconductor substrate; and forming individual semiconductor devices bydividing the semiconductor substrate along the division lines in thelongitudinal direction and lateral direction by applying an externalforce to said semiconductor substrate.
 5. The method of manufacturing asemiconductor device according to claim 4, wherein in said step offorming the modified regions inside said semiconductor substrate, thenumber of times of scanning laser light along the division lines wheresaid grooves are formed is smaller than the number of times of scanningthe laser light along the division lines where no groove is formed. 6.The method of manufacturing a semiconductor device according to claim 5,wherein said step of forming the grooves by etching continuously on onlysaid division lines formed parallel in one direction is performedsimultaneously by anisotropic etching which forms diaphragm structuresin said semiconductor substrate.
 7. The method of manufacturing asemiconductor device according to claim 4, wherein said step of formingthe grooves by etching continuously on only said division lines formedparallel in one direction is performed simultaneously by anisotropicetching which forms diaphragm structures in said semiconductorsubstrate.
 8. The method of manufacturing a semiconductor deviceaccording to claim 4, wherein the grooves formed on said division linesare V-grooves.
 9. The method of manufacturing a semiconductor deviceaccording to claim 5, wherein the grooves formed on said division linesare V-grooves.
 10. The method of manufacturing a semiconductor deviceaccording to claim 6, wherein the grooves formed on said division linesare V-grooves.
 11. The method of manufacturing a semiconductor deviceaccording to claim 7, wherein the grooves formed on said division linesare V-grooves.
 12. A semiconductor device manufactured by the method ofmanufacturing a semiconductor device according to claim 4, whereinchamfering is performed for only two sides opposed to each other in aback surface side of each of the individual semiconductor devices. 13.The semiconductor device according to claim 12, wherein a diaphragmstructure is formed in said semiconductor device.
 14. The semiconductordevice according to claim 13, wherein said two sides opposed to eachother with the chamfers formed are long sides of said semiconductordevice.
 15. The semiconductor device according to claim 11, wherein saidtwo sides opposed to each other with the chamfers formed are long sidesof said semiconductor device.